The Nurse Is Calculating the Medication Dose for a 4-Year-Old

The nurse is calculating the medication dose for a 4-year-old child by use of the body weight method. Which is a disadvantage of this type of drug dosage?
A) It does not account for metabolism and elimination.
B) It uses calculation of milligrams of drug and child's weight.
C) It utilizes the serum concentration of the drug and the proportion of the body weight.
D) It is not as easy to calculate as the body surface area method.